Chris Isidore from CNN Money published a well-researched update on the bailout black holes of Fannie & Freddie last week, and the outlook for taxpayers is not especially positive. Mortgage analyst for KBW, Bose George, estimates that by the end of 2010, the bailout tally could hit the $200 billion mark for each of the mortgage giants.

The first big government bailout of the financial crisis -- the takeover of mortgage finance giants Fannie Mae and Freddie Mac -- is poised to be the most expensive and complicated to complete.

Since Congress essentially wrote a blank check to the Treasury Department in July 2008 to do what needed to be done to inject capital into the two firms, Fannie (FNM) has received $34.2 billion of direct government support while Freddie (FRE) has received $51.7 billion.

While that's lower than the $117.5 billion poured into insurer AIG (AIG) by the Federal Reserve and the $200 billion given to the nation's largest banks through the Troubled Asset Relief Program, or TARP, the current cost of the Fannie and Freddie bailouts dwarfs original estimates from a year ago

When Congress was debating the bailout of Fannie and Freddie last July, the official estimate from the Congressional Budget Office was that a bailout would most likely cost taxpayers $25 billion, with only a 5% chance of the price tag reaching $100 billion between them.

In addition, both Fannie and Freddie are likely to need billions of dollars more after they report second quarter results in the coming weeks. Experts believe the cost will only continue to rise in the next year.

"We're assuming they each will cross the $100 billion mark fairly soon. They could be hitting the $200 billion barrier by the end of next year," said Bose George, mortgage analyst at Keefe, Bruyette & Woods, an investment bank specializing in financial services firms.

The direct government aid has helped keep the two troubled firms solvent. The amount of any additional aid will be determined by their ongoing losses and reserves for future losses on the trillions of dollars in mortgage loans they own or guarantee.

Fannie and Freddie were originally created to help ensure that financing for homes would be available and affordable to more consumers. The two firms buy mortgages from banks and other lenders and bundle them together into securities. They then either hold those securities or sell them to them to investors with a guarantee that they will be paid the money owed by homeowners.

But as more homeowners continue to default on mortgages, the two firms will likely book additional losses well into next year.

Neither firm has given an estimate as to how high losses will reach. But the original limit of $100 billion in losses set in place when the government put Fannie and Freddie into conservatorship, essentially a form of bankruptcy, last September was quickly raised early this year to $200 billion each because of concerns about looming losses.

In return for pumping taxpayer dollars into the two firms, Treasury received preferred stock, which is designed to give the government a healthy 10% to 12% dividend. But few expect that Fannie or Freddie will be able to pay that dividend, let alone return the money handed to the firms to cover their losses..

Even James Lockhart, director of the Federal Housing Finance Agency, the government body that has overseen the two firms since they were placed into conservatorship, said it will be a challenge for Fannie and Freddie to make their scheduled payments.

"Obviously the 10% dividend is a high rate," he said, but added that this is probably below what private market investors would demand to own preferred shares in the two companies.

Lockhart also agrees with experts who believe that the government will eventually have to write down at least a portion of the money that has been sunk into Fannie and Freddie. He would not estimate how much, saying it will depend upon housing prices in the future.

But Lockhart maintained that the loss of taxpayer money is worth it in the long run because Fannie and Freddie have continued to be vital parts of the housing market during the credit crunch.

"They really have been the backbone of the housing market throughout this period," he said. "The money spent, we can at least say has gone to a good cause -- keeping the housing market much more stable than it would have been [without the bailout]."

And it's precisely for this reason that experts think the ultimate bailout cost will climb much higher. The money allocated for Fannie and Freddie is being used not to simply return the firms to profitability, but to try and fix the broader housing market's problems.